INV ITEDP A P E R

State of the Art in Stereoscopicand Autostereoscopic DisplaysThis overview covers most of the 3-D displays that are in use today and

presents recent developments and advances in this field.

By Hakan Urey, Senior Member IEEE, Kishore V. Chellappan,

Erdem Erden, Student Member IEEE, and Phil Surman

ABSTRACT | Underlying principles of stereoscopic direct-view

displays, binocular head-mounted displays, and autostereo-

scopic direct-view displays are explained and some early work

as well as the state of the art in those technologies are re-

viewed. Stereoscopic displays require eyewear and can be

categorized based on the multiplexing scheme as: 1) color

multiplexed (old technology but there are some recent devel-

opments; low-quality due to color reproduction and crosstalk

issues; simple and does not require additional electronics

hardware); 2) polarization multiplexed (requires polarized

light output and polarization-based passive eyewear; high-

resolution and high-quality displays available); and 3) time

multiplexed (requires faster display hardware and active

glasses synchronized with the display; high-resolution com-

mercial products available). Binocular head-mounted displays

can readily provide 3-D, virtual images, immersive experience,

and more possibilities for interactive displays. However, the

bulk of the optics, matching of the left and right ocular images

and obtaining a large field of view make the designs quite

challenging. Some of the recent developments using uncon-

ventional optical relays allow for thin form factors and open up

new possibilities. Autostereoscopic displays are very attractive

as they do not require any eyewear. There are many possibi-

lities in this category including: two-view (the simplest

implementations are with a parallax barrier or a lenticular

screen), multiview, head tracked (requires active optics to

redirect the rays to a moving viewer), and super multiview

(potentially can solve the accommodation–convergence mis-

match problem). Earlier 3-D booms did not last long mainly due

to the unavailability of enabling technologies and the content.

Current developments in the hardware technologies provide a

renewed interest in 3-D displays both from the consumers

and the display manufacturers, which is evidenced by the

recent commercial products and new research results in this

field.

KEYWORDS | Autostereoscopic; head-mounted displays; head

tracked; multiview; parallax barrier; stereoscopic; volumetric;

3-D displays

I . INTRODUCTION

The display industry is witnessing a major change from 2-D

to realistic 3-D as evidenced by the success of recent 3-D

movies and consumer 3DTV product offerings. It can be

envisioned that within the next few years a major share of

current displays will be replaced by 3-D displays or at least

by 3-D-capable displays and stereoscopic and autostereo-

scopic technologies are likely to play a major role.

The human brain extracts the depth information andperceives the stereoscopic views by fusing together the two

images acquired by the eyes. The disparity in these two

images (i.e., binocular disparity) is the most widely uti-

lized visual cue in displays to render a stereoscopic view.

Although this requirement was understood by Euclid, the

first stereoscopic device did not appear until 1832 when

Charles Wheatstone introduced the stereoscope [1]. For

producing a stereoscopic image there are many technol-ogies described in the scientific and patent literature

ranging from simple anaglyph methods to advanced auto-

stereoscopic and interactive techniques.

Manuscript received April 2, 2010; revised October 4, 2010; accepted

November 19, 2010. Date of publication January 28, 2011; date of current version

March 18, 2011. This work was supported by the European Commission within FP7

under Grant 215280 HELIUM3D. The work of H. Urey was supported by TUBA-GEBIP

Award.

H. Urey is with the Department of Electrical Engineering, Koç University, Istanbul

34450, Turkey (e-mail: hurey@ku.edu.tr).

K. V. Chellappan is with the University of Southern Mississippi, Hattiesburg,

MS 39406 USA (e-mail: vckishore@gmail.com).

E. Erden is with the Center for Research and Education in Optics and Lasers (CREOL),

University of Central Florida, Orlando, FL 32816 USA (e-mail: rdmrdn@gmail.com).

P. Surman is with the Imaging and Displays Research Group, De Montfort University,

Leicester LE1 9BH, U.K. (e-mail: psurman@dmu.ac.uk).

Digital Object Identifier: 10.1109/JPROC.2010.2098351

540 Proceedings of the IEEE | Vol. 99, No. 4, April 2011 0018-9219/$26.00 �2011 IEEE

Stereoscopic and autostereoscopic displays generally

exhibit accommodation–convergence (AC) mismatch

where the eyes converge at the apparent point of fixation

in the image but focus on the screen [2], [3]. This is an

unnatural condition that disrupts the correlation between

vergence and focal distance. The mismatch must be kept

within certain limits in order to prevent visual discomfort.

As AC mismatch occurs when the virtual position of anobject in the image is away from the plane of the screen

there is a limit below which the mismatch is acceptable. It

has been determined that the depth range should not exceed

13% of the viewing distance [4]. Other research [5] indicates

that the actual tolerable conditions for comfortable viewing

could be less restricted than those given in [4] and [6]. There

are also several solutions suggested in the literature to

overcome this limitation; these are reviewed later.Fig. 1 provides a classification for stereoscopic and

autostereoscopic technologies as well as an outline for this

paper. Direct view in the section titles refers to images

appearing on a flat screen, which can be a flat-panel display

or a projection system. Each section provides information

about how the technology works and gives an overview of

the literature and state of the art and provides examples of

commercially available products wherever possible. Otherimportant categories of 3-D displays such as holographic

and volumetric displays are discussed in other articles in

this issue. Sections II–IV give an overview of different

technologies and Section V summarizes the pros and cons

of each type of 3-D display reviewed in the paper and gives

author opinions about future directions.

II . STATE OF THE ART IN DIRECT-VIEWSTEREOSCOPIC DISPLAYS

This section reviews the current status of 3-D displays,

which require the viewer to wear special glasses in order to

perceive 3-D.

A. Color-Multiplexed ApproachThe classic example of a color-multiplexed 3-D visual-

ization method is that using anaglyph glasses. This is an

inexpensive solution to the 3-D visualization problem and

can be applied whenever common color video equipment

is available. Anaglyph 3-D images are produced by combin-

ing the images for the left and right eyes using a compli-

mentary color coding technique. This method has been

understood since the mid-1800s [7].The most common anaglyph method uses the red chan-

nel for the left eye and the cyan channel for the right eye.

The viewer wears a pair of colored glasses so that the left

and right eyes receive the corresponding images only. The

main drawbacks of this type of display are the loss of color

information and the increased degree of crosstalk. The

spectral response of the display and the anaglyph glasses,

image compression methods and image encoding, as well astransmission protocols have been cited as sources of cross-

talk [8], [129]. Anaglyph images are usually created either

by capturing the images with a binocular camera or by using

the depth information of the objects and only one image as

recently shown [9]. For reducing the crosstalk and in-

creasing the quality of the images, methods such as image

alignment, color component blurring, and depth map ad-

justment have been demonstrated with significantly im-proved image quality [10], [11], [130]. The anaglyph

viewing filters sometimes cause chromatic adaptation

problems in the viewer. Commercially available NVIDIA

and iZ3D drivers can output the imagery in this format [12].

ColorCode 3-D uses the color-multiplexed approach to

produce full color 3-D images, which are viewed with

amber and blue colored glasses. The 3-D information is

written as small variations in color and the full colorimages have faint halos of golden and bluish tints when

viewed with the naked eye [13]. The advantage is that it

works with the standard display hardware and can offer

full-color images at lower cost. The patented technique has

also been applied for the production of movies, games, and

mobile content. Ghosting and color reproduction issues

have not been completely overcome in this technology.

Another display which fits in this category but offers adistinctively higher image quality is the interference filter-

based method from Infitec GmbH (Ulm, Germany). Fig. 2

shows the projection scheme with these filters for

producing 3-D. Two full-color projectors are fitted with

narrowband interference filters, each having its own three

narrow transmission bands lying within the spectral

response of the red, green, and blue receptors of the eye.

The right and left images are projected onto a normaldiffusing screen through these filters and the eye wear

with the corresponding filters separates the full-color

image for left and right eyes. The crosstalk is reported to be

less than 1% for the entire spectral range [14]. The

technology is compatible with most of the image projection

methods available but requires the application of a color

gamut transformation algorithm to retain the original color

Fig. 1. Organization of the article.

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Vol. 99, No. 4, April 2011 | Proceedings of the IEEE 541

gamut. This system has been implemented at virtual reality

theaters with performance figures better than that of other

passive technologies discussed above [15]. An Infitec filter

wheel-based approach eliminates the cost and complexity

of using two projectors and the associated alignment

issues. In this case, the left and right images are presented

in a time sequential fashion by a single projector and a

rotating Infitec filter is used to encode the stereo pair.Images are projected onto a matte screen and the passive

Infitec filters worn by the viewers separate the images.

B. Polarization-Multiplexed ApproachIn this method, the state of polarization (SOP) of light

corresponding to each image in the stereo pair is made

mutually orthogonal. Linear or circular polarization can be

employed but the latter allows more head tilt before cross-

talk become noticeable. The viewer uses eyewear withappropriate polarizers to block the image not intended for

that eye. Images are produced by a two-projector setup in

which one projector produces either the left or right eye

images with a polarization state orthogonal to that of the

other projector. This method also requires the use of a

special screen that preserves the SOP. For rear projection,

a combination of Fresnel-lenticular surface can be used for

preserving the SOP while for front projection a silverscreen is used. A commercially available screen for front

projection is 3-D Virtual Grey from DaLite. For rear pro-

jection, Da-Lite produces a screen called 3-D Virtual Black.

Both screens are claimed to maintain 99% of polarized

light and have a gain of more than 1 [16].

Another method which reduces the complexity of using

two projectors uses a single projector equipped with an

electrically controllable polarization rotator synchronized

to the frames being displayed [17]. This method is cost

effective and requires no alignment. Such a device, called

ZScreen, is commercially available from RealD. This de-

vice utilizes a wire grid polarizer [18] combined with a

cleanup sheet polarizer and pi cells [19] for effectively

controlling the polarization direction [20]. Improved

device design by providing antireflection coatings to corecomponents, using more efficient polarizers and other

modifications has been recently reported [21]. As these

devices have a finite response time, blanking is necessary

between the left and right images in order to reduce

crosstalk; this in turn increases the light loss.

The difficulty in aligning two projectors, increased

cost, and power consumption may also be eliminated by

employing a single projection unit [22], [23]. In thismethod, light-emitting diode (LED) illumination was

used for the generation of two full-color images with

orthogonal polarization states by a single modulation unit

containing four liquid crystal on silicon (LCOS) devices

(two for each eye) and some polarization controlling

optics. HDI-US Inc. (Los Gatos, CA) developed a laser-

based high-definition (HD) display with a single light

engine module with two high-speed LCOS devices. Thisrear projection display has high frame refresh rate of

360 Hz and a screen diagonal size of 70–12000. It has also

been claimed to outperform most of the current display

technologies in terms of energy efficiency, color gamut,

picture brightness, and resolution [24]. A commercial

product with polarization multiplexing is the recently

announced single lens 3-D projector named CF3D from

LG Electronics (Seoul, Korea) [25].

Fig. 2. Schematic setup of the Infitec system for 3-D content display. The slightly differing spectral transmission curves of the filters

are also shown. From [14], with permission from The Society for Information Display.

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542 Proceedings of the IEEE | Vol. 99, No. 4, April 2011

For the flat panel display (FPD) types, available tech-nologies are micropolarizer based (�-pol or X-pol) [26],

patterned retarder based [27], active retarder based, and

dual-panel type. The first two cases work by reserving half

of the total horizontal lines of pixels for the right eye and

the other half for the left eye. Alternate horizontal pixel

rows are orthogonally polarized by the line-interleaved

micropolarizers attached to the display. Stereo pair images

are displayed in a horizontally interleaved format and thepassive polarizer glasses at the viewers eyes separate the

images. Although it loses half of the available resolution,

this system has the advantage of requiring only low-cost

passive glasses.

It has also been reported that a �-pol-based display can

be converted to an autostereoscopic display by adding two

more �-pol sheets, where one is movable [26]. The pat-

terned retarder approach also utilizes the same principlesbut uses different hardware and modified versions of the

technique for higher performance by reducing polarization

artifacts and dispersion [27], [28]. The optics of a pat-

terned retarder-based display is shown in Fig. 3. Methods

for fabricating these patterned retarder structures are also

described in the literature [29], [30]. Display products

utilizing this type of technology are available from

Hyundai (Korea) and JVC (USA). The problem of limitedviewing angle in the patterned retarder type displays can

be resolved by reducing the glass spacing between the

retarder layer and the liquid crystal layer [31], [32].

Dual-panel-type 3-D displays such as the ones from

iZ3D (San Diego, CA) use two stacked liquid crystal

display (LCD) panels of which one displays the images and

the other controls the outgoing polarization [33]. This

display is viewed with passive polarizer glasses.Although polarizing filters can cause chromatic aber-

ration, these types of 3-D displays offer high resolution and

the color quality issues are generally negligible, unlike the

anaglyph-based displays. Ghost images, hot spots, or abrupt

falloff of intensity could also arise due to an improper

choice of the projection lens focal length or the screen [34].

C. Time-Multiplexed ApproachThese displays exploit the persistence of vision of the

human visual system to give 3-D perception. In this tech-

nique, the left and right eye images are displayed on the

screen in an alternating fashion at high frame rates, usually

120 Hz. This is referred to as alternate frame sequencing

and the viewer is required to wear battery powered active

shutter glasses, which are synchronized to the content

being displayed. This is done either by using an infraredemitter or by the so-called DLP Link (Texas Instruments,

Dallas, TX), which uses encoded white light flashes

detected by the shutter glasses in between the left and

right frames. The liquid-crystal-based glasses block the

left-eye images from reaching the right eye of the viewer

and vice versa. An immediate disadvantage is the cost of

the active shutter glasses and the excess video bandwidth

required compared to 2-D. The single lens projectormodel PG-D45X3D from Sharp (Mahwah, NJ) utilizes the

DLP Link technology for 3-D capability [35].

Time-multiplexed 3-D displays are common in the

market with Samsung (Korea) and Mitsubishi (Japan)

leading with their 3-D-capable rear projection TVs [36]. A

time-multiplexed display with the capability of allowing

the user to interact with the images has been demonstrated

at Stanford University, Stanford, CA. The display, calledResponsive Workbench, used head tracking to render the

correct perspective [37].

Another commercially available projector with a single

projection unit and time-multiplexed output is the DepthQ

HD projector from Lightspeed Design, Inc. [38]. This pro-

jector uses a digital light processor (DLP) module from

Texas Instruments for forming images that are viewed with

active liquid-crystal-based shutter glasses. The advantagesof this type of 3-D display are that they do not require a

special screen and a single projection unit with a higher

video bandwidth is sufficient.

The time-multiplexed approach has also been em-

ployed in immersive displays; one notable example is the

Cave Automatic Virtual Environment (CAVE) system from

Fig. 3. The structure of a patterned-retarder-type display. Linearly polarized light is used to illuminate the LCD panel with a patterned

retarder plate where alternate strips offer half-wave retardation, which rotates the plane of polarization by 90�; the full quarter wave plate

transforms the linearly polarized light into left and right circularly polarized light. At the viewer’s eyes circular polarizer (combination of

quarter wave plate and a linear polarizer) glasses are used to separate the views. Only half of the horizontal lines of pixels on the LCD are used to

form the right or left image. From [27], with permission from The Society for Information Display.

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Vol. 99, No. 4, April 2011 | Proceedings of the IEEE 543

the University of Illinois, Chicago [39]. The system was acube of 10 ft3 in size where the walls served as screens onto

which the images were rear projected. This system offered

an immersive feeling to the viewer inside the cube; the

development of later versions of this system has been

discussed in [40].

Having considered most of the promising stereoscopic

3-D display technologies it is clear that each technology

has its own advantages and limitations. For the hometheater market projection systems employing a Zscreen

and passive polarizer glasses could be a lower cost solution

as the polarizer glasses required for each viewer are

inexpensive and do not require the careful handling of the

expensive shutter glasses. Possible disadvantages with this

approach are the difficulty in setting up a reflective screen,

the need to minimize the artifacts mentioned earlier, and

ghosting effects due to the imperfect polarizers and screen.For portable desktop displays there exists a multitude

of choices employing different techniques explained

before. Here also, the choice is between shutter-glass-

based or polarizer-based displays. Passive glass-based dual-

panel displays offer full resolution and the reduction in

luminance can be compensated by using more powerful

backlight sources. Frame-sequential-type displays (also

known as page flipping displays) also offer full resolutionover line-interleaved-type micropolarizer-based systems.

Though the choice is up to the viewer, presumably one

would prefer a system with low cost, high resolution, good

luminance, and less sophisticated viewing aids.

III . HEAD-MOUNTED DISPLAYS

Developing display systems that can provide the viewerwith a sense of immersion is another active topic of re-

search. This section briefly discusses the techniques and

progress in this area.

A. Head-Mounted Displays (HMDs)Head-mounted stereoscopic displays are binocular sys-

tems with two separate image generators and they employ

relay optics [41]. As these are head-worn by the user, mo-bility is available without interrupting the 3-D view giving

a feeling of immersion in the scenes being displayed. At-

tempts to provide the viewer with a feeling of immersion

dates back to the late 1950s when Morton Heilig im-

plemented the Sensorama Simulator [42]. Now such sys-

tems are far more advanced and widely used for training

purposes in the medical, military, and industrial fields and

employ HMDs for producing the virtual environment.Augmented reality (AR) systems, a subclass of mixed real-

ity (MR) systems, make use of see-through HMDs to

enhance the viewer’s understanding of the real-world in-

formation by providing him/her with computer-generated

information superimposed on the real-world scenes [43].

The video see-through approach superimposes the real-

world images acquired through a video camera with the

virtual world information from a computer whereas the

optical see-through method uses precision eye-pupil track-

ing. Thus, video see-through methods generally produce

better results than the optical see-through approach where

registering the real-world scene with the virtual image

is difficult [44]. One of the notable advances is in themedical field where surgeons can have detailed computer-

generated information superimposed on the patients

in real time: the so-called computer-aided surgery

(CAS) system. Ferrari et al. recently reported such an

MR system (Fig. 4) in which both real-world information

and computer-generated images were superimposed uti-

lizing a video see-through approach [45].

Achieving large field of view (FOV) and high resolutionsimultaneously has been a problem in the case of HMDs.

Optical tiling, presenting a small high-resolution inset

image and a low-resolution background based on user

pupil tracking, is one of the solutions proposed to address

the requirement of high FOV and high resolution [46],

[47]. Sensics Inc. (Columbia, MD), one of the pioneers in

HMD technology, offers high-resolution displays with up

to 180� diagonal FOV [48]. The unit, named piSight,utilizes 12 microdisplays to create a concave wraparound

display for each eye as shown in Fig. 5.

There are many HMD products currently available

from different companies such as Vuzix Corporation

Fig. 4. An MR system setup and the mixed reality views through

the HMD. From [45], with permission of IEEE.

Fig. 5. The Sensics piSight HMD showing tiled microdisplays.

Image courtesy of Sensics Inc.

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544 Proceedings of the IEEE | Vol. 99, No. 4, April 2011

(Rochester, NY), Fifth Dimension Technologies (Irvine,CA), Cybermind (Maastricht, The Netherlands), i-O

Display Systems LLC (Sacramento, CA), etc.

In common with other 3-D display technologies, 3-D

HMDs also have the problem of AC mismatch and the

problem becomes less noticeable as the image plane is

moved towards infinity [5]. To solve the AC mismatch

issue, systems with discrete (multifocal) or continuously

variable (vari-focal) focal plane locations have been pro-posed [49]. The systems can be made with active optics,

which forms virtual images with focal plane adjustment

based on the feedback from a user-gaze detection circuit

[50] or with no moving parts [51]. Optical see-through

HMDs with large focal depth have been proposed for solv-

ing the AC conflict utilizing a modified Maxwellian view

with increased viewing area. This method utilizes holo-

graphic optical elements and claims that 3-D images can beproduced at any distance from the viewer [52]. Recently, a

liquid lens with adjustable focal length has been utilized in

making HMDs, which can operate either in multifocal or

vari-focal mode [53]. Moving the location of the virtual

image of the display screen by means of a relay lens

movable along the optic axis is also a technique that was

proposed to eliminate the AC mismatch problem [54].

In order to reduce the form factor of the HMD, theoptical path may be folded using prism arrangements [55].

One of the main challenges associated with the develop-

ment of these types of binocular 3-D display is the visual

discomfort due to the differences in the left and right eye

images resulting from the mismatch in the optical per-

formance of each channel. As the human visual system

depends on many visual cues and internalized patterns to

interpret a 3-D scene, even the smallest errors can give riseto visual discomfort. HMDs utilize two separate displays;

thus mismatch in any of the optical properties or alignment

issues of the components used in the optical train of the left

and right channels becomes critical [56], [57]. Refer to [58]

for a discussion on the optical design problem of HMDs.

IV. STATE OF THE ARTIN AUTOSTEREOSCOPICDIRECT-VIEW DISPLAYS

Autostereoscopic displays create images with the required

disparity at the exit pupils without requiring any form of

special glasses or other user-mounted devices. Two-view

(binocular) and multiview systems with fixed viewing

zones and head/pupil tracked and super multiview (SMV)

systems are different types of autostereoscopic displaysdiscussed in detail in the following sections. In two-view

displays, only a single stereo pair is displayed, whereas in

multiview displays, multiple stereo pairs are produced to

provide 3-D images to multiple users. In autostereoscopic

displays, large Fresnel lenses, lenticular arrays, parallax

barriers, or other components such as holographic ele-

ments (HOEs), mirrors, micropolarizers, and prisms are

used to control light paths and to form exit pupils. Inautostereoscopic displays with fixed viewing zones, these

components are used to create fixed exit pupils where the

user’s left/right eyes must be positioned. On the other

hand, head/pupil tracked displays create exit pupils ac-

cording to the viewer’s eye pupil locations and enable the

viewer(s) to see stereo comfortably without having to

remain stationary. In SMV systems, a large number of

views are produced in order to create smooth motionparallax across the viewing field.

A. Two-View Autostereoscopic DisplaysTwo-view systems are 3-D displays where a single pair

of parallax views is produced. In two-view systems, the

stereo pair can be formed at a single location or the pair

can repeat itself in multiple zones in space (i.e., multi-

viewer). The viewers’ eyes have to be in the correct loca-

tion within the ideal distance to perceive a stereoscopic

image. Two-view systems with a head tracker can provide

the same stereo pair to a single viewer or to multipleviewers and enable a greater freedom of movement.

1) Parallax Barrier Systems: LCD elements are commonly

used in 3-D displays since they offer good pixel position

tolerances and high position stability, have carefully con-

trolled glass thickness, and can be successfully combined

with different optical elements [59]. Image quality issues

of 3-D displays based on LCD panels and solutions to im-prove their performance are available in the literature [60].

LCDs and other pixelated emissive displays are suitable

for autostereoscopic displays as they can be combined with

parallax barriers. As can be seen in Fig. 6, left and right eye

image columns are placed alternately on the display and

the parallax barrier, which is composed of vertical aper-

tures separated by black masks, allows light to pass only to

the desired viewing zone. The ratio of the display pixel

Fig. 6. Parallax barrier working principle illustration. The same stereo

pair repeats itself along the viewing zone. If the parallax barrier can

be turned on/off electronically, the system is 3-D/2-D switchable.

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Vol. 99, No. 4, April 2011 | Proceedings of the IEEE 545

width to the barrier pitch depends on the distance betweenthe right and left viewing points [61]. The system de-

scribed below creates repeated viewing zones along the

width of the display; therefore it can also be used to create

a multiview system.

The loss of brightness caused by the barriers and the

loss of spatial resolution caused by using only half of the

pixels for each viewing zone are the two problems asso-

ciated with the parallax barrier systems. There is also atradeoff between light efficiency and crosstalk level due to

the aperture size. It has been shown that with a slanted

barrier system, higher efficiency can be achieved while

keeping the same crosstalk level [62]. Using aperture grills

as a parallax barrier instead of black stripes on an acrylic

increases the contrast by eliminating the reflection on the

surface and provides better transmittance [63], [64].

In parallax barrier systems, the optimum viewing dis-tance is proportional to the distance between the display

and the parallax barrier and inversely proportional to the

display pixel size. As the display resolution gets higher, the

optimum viewing distance of the system gets longer. A

method to improve the resolution using four views instead

of two views employs parallax polarizer barriers combined

with a special backlight [65].

Using two LCD elements and directing their content totwo different eyes with the help of two parallax barriers is

another method of increasing the spatial resolution of the

parallax barrier systems. Sharp has produced a twin LCD

display in which the viewing zones for left and right eyes

are formed by two LCD displays where each includes a slit

array and a microlens array. These are combined with a

beam combiner and the images are transmitted to the

viewer’s corresponding eyes [66]. The display includes ahead tracker and the viewing zone positions can be

changed dynamically by moving the two parallax slit arrays

simultaneously along the LCD plane [59].

In 1994, Sharp announced their first single-panel 3-D

display [67] based on the parallax barrier method. In 1996,

the design was improved with the invention of viewing

position indicator (VPI). VPI is a solution to the practical

problem of finding the best viewing position. As explainedbefore, the parallax barrier system creates repeating

viewing zones for left and right eyes and if the viewer’s

left eye is placed in a right eye viewing zone, a reversed

stereoscopic (pseudoscopic) image is perceived. In systems

with VPI, a few rows of pixels at the bottom of the display

are used for displaying color indicators to aid the user to

find the correct viewing location.

Parallax barrier systems can be 2-D/3-D switchable byremoving the optical function of the parallax elements

[67]. The barriers can be optically switched by using

polarization-based electronic switching systems. In 2001,

Sharp produced a display that could be electronically

switched between two different modes [68]. In this sys-

tem, the 2-D/3-D switching is achieved by the use of a

patterned retarder parallax barrier, which includes a com-

ponent that can rotate the polarization of light (3-D) orleave it unaffected (2-D). Crosstalk and white level varia-

tion in the 3-D mode of this display were estimated by

using a model based on Fresnel diffraction [69]. The im-

provements in OLED technology increased their usability

in 3-D displays and Samsung announced a new 1400 WXGA

full resolution 2-D/3-D OLED display prototype with fast

switching parallax barrier [70].

Another design parameter for parallax barrier systemsis the location of the parallax barrier relative to the display

unit. Placing the parallax barrier at the rear of the display

(between the backlight and LCD) results in lower cross-

talk. On the other hand, placing the barrier in the front

(between LCD and the user) results in better intensity

uniformity and an optimum barrier pitch is required for

reducing the crosstalk in this configuration [67].

In fixed parallax barrier systems, the pitch of thebarrier is determined before the system is constructed and

cannot be changed later. This causes a fixed viewing dis-

tance and viewing zone depth. When the system is used for

more than one viewer with head tracking, calculation of

optimum barrier parameters gets more difficult.

A solution for eliminating the fixed viewing distance

and fixed viewing zone limitations can be obtained by

dynamic parallax barriers instead of static ones. Dynamicparallax barrier system, Dynallax, uses a dual-stacked LCD

monitor and a dynamic barrier and the system has a longer

operating range. The dynamic barrier is rendered on the

front display, and a modulated virtual environment, which

is composed of two or four channels, is rendered on the

rear display [71]. It is a 2-D/3-D switchable system, which

supports two viewers with the use of a head tracker. The

system has less brightness, resolution, and contrast com-pared to a static barrier system. Synchronization between

the front and rear screens is critical for good image quality.

Parallax barriers can be used with projectors to create

autostereoscopic 3-D projector systems as shown in Fig. 7

[72]. The system is composed of multiple 2-D projectors, a

projection screen, and two parallax barriers. The first

parallax barrier controls the output of the projectors such

that the size of image pixels on the projection screen ismatched with the second parallax barrier’s pitch. The

second parallax barrier works as a regular parallax barrier

and directs the parallax images to the viewers’ eyes.

2) Lenticular Systems: As can be seen in Fig. 8, lenticular

systems combine cylindrical lenses with FPDs to direct the

diffused light from a pixel such that it can only be seen in a

certain viewing angle in front of the display. The displaycreates repeating viewing zones for the left and right eyes

(shown with green and red colors). Similar to parallax

barrier systems when the viewer’s left eye is placed in a

right eye viewing zone the viewer observes a pseudoscopic

image. Information about efficient lenticular lens design,

analysis methods, and recent advances in the technology

can be found in [73] and [74].

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546 Proceedings of the IEEE | Vol. 99, No. 4, April 2011

The alignment of the lenticular array on the displaypanel is critical in lenticular systems. This alignment gets

more difficult as the display resolution increases and any

misalignment can cause distortions in the displayed

images. Software-based solutions that compensate for the

production errors can be used to improve the quality of the

lenticular systems [75]. Another problem with the lenti-

cular systems is the intensity variation along the viewing

zone due to beams coming from the subpixel regions of thedisplay panels. As the viewer changes the viewing angle, a

pattern of dark and bright bands is observed. This effect

can be decreased by slanting the lenses and adjusting the

focal length and pitch of the lenticular array elements [76].

As explained before, 2-D/3-D switchability is a usefulfunctionality for 3-D displays. A lenticular display can

switch between two viewing modes by using lenticular

lenses filled with a special material that can switch be-

tween two refracting states. Boer et al. used liquid crystal

(LC)-filled lenticular lenses that can be switched elec-

tronically between refracting (3-D) and nonrefracting

(2-D) modes [76]. The disadvantage of this display com-

pared to parallax barrier switchable displays is the residuallens effects at oblique angles even when the display is

working in the 2-D mode.

B. Multiview Autostereoscopic DisplaysIn multiview displays with fixed viewing zones, multi-

ple different stereo pairs are presented across the viewing

field. Users’ left and right eyes lie in two adjacent regionsthat have different perspectives. The number of views in

multiview displays is too small for continuous motion

parallax, but various methods have been used to keep the

apparent image content close to the plane of the screen

and minimize the large transitions between the views [77].

Newsight GmbH (New York) produces multiview displays

with reduced transition zones and suppressed glare with

screen sizes up to 18000 (the world’s largest) [78].As discussed before, static parallax barriers combined

with pixelated emissive displays create repeated viewing

zones. In multiview parallax barrier systems, more than

two images can be created in the viewing zone to produce

motion parallax. Sanyo has produced a multiview image

integration system such that seven parallax video images

can be combined together into a single video that can fit

into the special step barrier they developed [79], [80].Endo et al. used parallax barriers to create a cylindrical

3-D display that is based on parallax panoramagram to

show 3-D images to multiple viewers from 360� of arc

horizontally without 3-D glasses [81]. A cylindrical paral-

lax barrier and a rotating 1-D light source array are used in

an experimental cylindrical display system with the reso-

lution of 1254 pixels circularly and 128 pixels vertically.

Each pixel has a 60� viewing angle that is divided into 70views to create a smooth parallax around the display.

Time multiplexing is another method that can be used

to produce multiview autostereoscopic displays with

parallax barriers. Choi et al. fabricated a 3-D display with

increased viewing zones by using dynamic barriers located

between the lens array and the display panel [82].

Lenticular arrays combined with pixelated emissive

displays can also be used to create multiview 3-D displays.The problem with lenticular systems is the reduction in

resolution with the increase in the number of viewers. In

vertically aligned lenticular arrays, the resolution de-

creases in the horizontal direction only, however if the

lenses are slanted the resolution loss is distributed into two

axes [76]. Philips (Eindhoven, The Netherlands) produced

a slanted lenticular screen that can support 7–15 views

Fig. 8. Illustration of the working principle of a lenticular screen.

The same stereo pair repeats itself along the viewing zone. If refraction

through lens is turned on and off electronically, the system switches

between 2-D and 3-D.

Fig. 7. Parallax-based autostereoscopic 3-D projector. The first

parallax barrier controls the output of the projectors and the second

parallax barrier directs the parallax images to the viewers’ eyes.

Adapted from [72].

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Vol. 99, No. 4, April 2011 | Proceedings of the IEEE 547

depending on model, and the structure of the screen is

shown in Fig. 9 [83].

The figure shows the relationship between the pixels

and the slanted lenticular sheet for a seven-view display. Asthe LCD is located in the focal plane of the lenticular sheet,

the horizontal position on the LCD corresponds to the

viewing angle. Therefore, all points on line XX direct view 3

in a given direction, and all points on line YY direct view 4

in another direction. The way in which the effect of flipping

is reduced is evident by examining line XX where view 3

predominates, but with some contribution from views 2

and 4. Similarly, for the angle corresponding to line YY,view 4 with some contribution from views 3 and 5 is seen.

Implementing autostereoscopic methods in mobile

displays is a promising field of study due to increased

public interest in 3-D displays. Sharp introduced the first

mobile phone with 3-D capability in early 2000 and sold

more than 1 million units [84]. Different mobile 3-D ap-

proaches can be found in the literature. Bilkent University,

New York, NY, leads a consortium of academic and indus-trial groups that address various aspects of 3-D mobile

phone technology [85]. In a recent study, an autostereo-

scopic 3-D solution for mobile displays has been demon-

strated by using 3-D film, directional backlight, and an

LCD panel. In this time-sequential autostereoscopic 3-D

display approach, the two different views created by

changing the direction of the light in a light guide are

directed to two different eyes by using a specially designed

3-D film [86]. New directional backlights for autostereo-scopic display applications that can be scanned 16� have

also been announced [87]. The multiview approach can

also be applied to mobile displays. The images captured by

a calibrated multi-imager camera array can be projected

onto a retroreflective screen by using multiprojectors [88].

In this configuration, multiple views can be created along

the viewing field. Special screens play an important role in

mobile 3-D displays [89].

C. Head-Tracked DisplaysHead-tracked displays can be divided into the following

principal categories: Fresnel lens, lenticular, projection,

and parallax barrier. In addition, other techniques

including prismatic and holographic can be employed.

In the 1990s, Sharp Laboratories of Europe developed a

system where the images from two LCDs are combinedwith a semisilvered mirror [90]. A display operating on a

similar principle was described by the Japanese Sea Phone

company [91] where the illumination is provided from two

monochrome displays, and the Massachusetts Institute of

Technology (MIT) Media Lab described the use of an SLM

that rotates the polarization by 90� in order to produce exit

pupils [92]. The Korea Institute of Science and Technology

display projects the images of two LCD panels on to aFresnel lens [93].

The simplest lenticular screen method is to place a

screen with vertical lenses in front of an LCD and swap the

images on the pixel rows to ensure that the eyes never see

pseudoscopic images [94]. Sharp developed a display where

a novel LCD mask structure provides contiguous light

across the viewing field [59]. The majority of projection

stereoscopic displays operate on the principle of formingreal images of the projector lenses in the viewing field.

The four main classes of projection display are

determined by the screen type. These are all described in

[95] and are: retroreflecting [96], [97], double lenticular

screen [98], [99], mirror [100], and lens [101].

Parallax can be used in various ways in a head-tracking

display. In a method proposed by Hattori [102], a parallax

barrier was used to block the light from a pair of projectorsthat form exit pupils by utilizing a large convex mirror. In

the Varrier display of the University of Illinois, a physical

parallax barrier with vertical apertures is located in front of

the screen [103]. Light is steered with the use of a dynamic

virtual barrier. The parallax display of New York Univer-

sity (NYU), New York, uses a fast dynamic parallax barrier

located in front of the display [104].

There are several methods of producing a head-trackingdisplay; among these are prismatic arrays, macrolens

arrays, and HOEs. Dresden University, Dresden, Germany,

has developed a display that replaces a parallax barrier with

a prism array [105]. Exit pupils can also be produced by

HOEs [106].

The single-user Free2C display developed at Fraunhofer

Heinrich Hertz Institute (HHI) overcomes the problems of

Fig. 9. Illustration of the working principle of a slanted lenticular

screen. LCD is located one focal length behind the lenticular sheet.

From [83], with permission from SPIE.

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548 Proceedings of the IEEE | Vol. 99, No. 4, April 2011

restricted viewer movement by using head tracking to makethe viewing sweet spot follow the position of the head

[107]. A head tracker determines this position and controls

a vertically aligned lenticular screen located in front of an

LCD to enable the viewer movement in both X and Z

directions. It achieves this by moving the lenticular screen,

also in the X and Z directions, with mechanical actuators.

This display can also be incorporated into a kiosk (Fig. 10)

where user’s gestures are recognized; this enables simpleintuitive handling of objects within the image. Three-

dimensional objects floating in front of the display can be

rotated by using gestures, and virtual buttons can be

pressed simply by pointing at them (virtual 3-D touch

screen). The Free2C kiosk is perfectly suited for applica-

tions in high-tech showrooms, convention halls, airports,

shopping malls, and department stores.

The SeeFront company in Germany produces a single-user 2200 head-tracked display that, like the Fraunhofer

HHI display, uses a lenticular screen in front of an LCD

[108]. In this case, there are no moving parts and the

images are directed to the viewer’s eyes by switching the

LCD subpixels.

There are also holographic and hybrid display solutions

with viewer tracking where both conventional and

holographic technologies are employed such as the SeeRealdisplay system [109]. The MUTED display system [110]

developed within a European-Union-funded project is also

a hybrid approach and uses a multiuser head tracker, and its

output is a spot pattern that is converted by the optical array

into a series of collimated beams that intersect at the

viewers’ eyes. The intersection regions are referred to as

exit pupils and are capable of movement over a large region.

A multiviewer laser-based 3-D autostereoscopic displayis under development in the HELIUM3D project [111],

[112]. Fig. 11 is a simplified schematic diagram. The system

does not incorporate a flat panel display and image infor-

mation is supplied by a fast light valve (LV) that controls

the output of red, green, and blue (RGB) lasers. The high

display frame rate permits many modes of autostereosco-

pic operation to multiple mobile viewers due to the ability

of the display to present a different image to every eye.

D. Light Field Displays

1) Super Multiview: An SMV display is a multiview dis-

play where the number of discrete images presented is

sufficiently large to give the appearance of continuous

motion parallax [114]. There is no AC mismatch and re-

search has been carried out into the number of views re-

quired for this condition. According to Takaki from Tokyo

University of Agriculture and Technology, Tokyo, Japan,

when the angle pitch of the directional rays is 0.2�–0.4�,more than two directional rays passing through a point in

3-D space enter the viewer’s eye simultaneously so that the

viewer’s eye can focus on that point as illustrated in Fig. 12

[115]. No discrepancy appears between the convergence

function and the accommodation function so that the dis-

play does not induce visual fatigue. Takaki presents an

SMV projection configuration with 64 views on a 9.2-in

screen size.A system has been demonstrated at CeBIT 2010 by

Sunny Ocean Studios (Singapore) [116] that can supply 64

viewing zones. This capability qualifies this as being SMV

but still does not quite fulfil the criteria set out in the

references for smooth motion parallax.

In some other types of displays, discrete beams of light

that vary with angle radiate from each point on the screen.

Fig. 10. Free2C interactive kiosk. User handling a multimedia

application on the computer without using keyboard or mouse

made possible with contact-free interaction technology and

autostereoscopic displays.

Fig. 11. HELIUM3D simplified schematic diagram of display. Multiple

exit pupils are formed dynamically by controlling light directions with

an SLM during the period of a horizontal scan [111], [113]. The pupil

tracker uses digital cameras and custom software to acquire and track

user’s eye pupil locations and serves as the dynamic feedback for

adjusting the exit pupil locations. Reprinted with kind permission of

the HELIUM3D consortium, which the authors are part of.

Urey et al. : State of the Art in Stereoscopic and Autostereoscopic Displays

Vol. 99, No. 4, April 2011 | Proceedings of the IEEE 549

These can take two forms. In the first type, optical modules

provide multiple beams that either converge and intersect

in front of the screen to form real image Bvoxels[ or diverge

to produce virtual Bvoxels[ behind the screen (Fig. 13). The

screen diffuses the beams in the vertical direction only

allowing viewers vertical freedom of movement without

altering horizontal beam directions. As the projectors/optical modules are set back from the screen, mirrors are

situated on either side in order to provide virtual array

elements on either side of the actual array.

Each screen pixel has a number of discrete emission

angles controlled by the image generators behind the

screen. Although this class of display is not volumetric, the

term Bvoxel[ is used to refer to the regions of image space

over which an apparent solid pixel is formed.

Examples of this type of display are Holografika

(Budapest, Hungary) [117], QinetiQ (Hampshire, U.K.)

[118], and Koc University, Istanbul, Turkey [119]. Holo-

grafika refers to its display as pseudoholographic displayand can currently supply a 3200 display using 9.8 megapixels

and a 7200 version with 34.5 megapixels [120]. The QinetiQ

display (see Fig. 14) appears to operate on the same

principles but uses projectors instead of the optical

modules of Holografika. Koc University also developed a

concept based on using an array of scanners made of

standard printed circuit board (PCB) material [121], where

each module carries an array of LEDs on the movingplatform to replace the array of microdisplay panels used by

Holografika (illustrated in Fig. 15) [119]. Another type of

display uses a fast frame-rate projector in conjunction with

a horizontally scanned dynamic aperture as in Fig. 14.

Although the actual embodiment appears to be totally

different from the multiple beam approach, the effect is the

same; in the case of the dynamic aperture the beams are

Fig. 12. Three-dimensional supermultiview images displayed with

high-density directional rays (reproduced from [115] with permission

from IEEE).

Fig. 13. Holographika display. Multiple beams either converge and

intersect in front of the screen to form real image ‘‘voxels’’ or diverge

to produce virtual ‘‘voxels’’ behind the screen.

Fig. 14. Dynamic aperture display. A horizontally scanned vertical

dynamic aperture directs the light from images produced on

a fast projector located behind it.

Fig. 15. Display developed at Koc University using a large array of

FR4 scanners [121] integrated with LED array and lenses.

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550 Proceedings of the IEEE | Vol. 99, No. 4, April 2011

formed in temporal manner. An early version of this type ofdisplay used a mechanically scanned aperture with the

images supplied by a cathode ray tube [122]. More recently,

this has been developed further at Cambridge University,

Cambridge, U.K., with the use of a fast digital micromirror

device (DMD) projector and a ferroelectric shutter [123].

Kajiki developed a concept called focused light array that

uses an array of light sources and scanners to create an SMV

display [124].Integral imaging displays, an early light field technique

first proposed in 1908, use an array of small lenses used to

produce a series of elemental images in their focal planes.

If the lens array is a 2-D fly’s eye lens, then motion parallax

in both horizontal and vertical directions is provided.

NHK, Japan, has carried out research into integral

imaging for several years; this includes one approach using

projection [125]. In 2009, NHK announced it had devel-oped an Bintegral 3DTV[ achieved by using a 1.34-mm

pitch lens array that covers an ultrahigh definition panel.

Hitachi has demonstrated a 1000 Bfull parallax 3-D display[that has a resolution of 640 � 480. This uses 16 projectors

in conjunction with a lens array sheet [126] and provides

vertical and horizontal parallax. There is a tradeoff be-

tween the number of Bviewpoints[ and the resolution;

Hitachi uses sixteen 800 � 600 resolution projectors andin total there are 7.7 million pixels (equivalent to a reso-

lution of 4000 � 2000 pixels).

V. CONCLUDING REMARKS AND THEFUTURE OF 3-D DISPLAYS

Three-dimensional displays have many applications and a

large range of 3-D demonstrators and products have re-cently been introduced to the market. This section pro-

vides the authors’ opinions about the future research

directions with the conviction that 3-D display users are

unlikely to accept a compromise on image quality and re-

solution while switching from 2-D to 3-D displays.

One of the important requirements for wide accep-

tance from the users is that products must allow seamless

switching between 3-D and 2-D modes. Though choice isup to the viewer, presumably one would prefer a system

with no restriction on user movement, low cost, high re-

solution, good brightness, and absence of (or at least low

cost and maintenance-free) viewing aids. Visual discom-

fort due to asymmetries in brightness, geometry, and im-

perfect temporal parallax are also issues that need to be

addressed. Crosstalk is another serious artifact present in

almost all types of stereoscopic displays but this can bebrought to an acceptable level by employing suitable image

processing algorithms and optimized display and capture

hardware. A display technique with zero crosstalk and ac-

ceptable image quality is still not available.

1) Stereoscopic Direct-View Technologies: Anaglyph meth-

ods are simpler than others; however, the image quality is

not sufficient for wide adoption due to the poor color re-production and crosstalk issues. These technologies are

likely to be limited for distribution of 3-D pictures in

printed media and as multimedia content that can be seen

on regular 2-D TV sets with simple and low-cost glasses.

Polarization-based 3-D displays offer important advantages

for the eyewear as they are very inexpensive, lightweight,

and passive (no batteries).

In the stereoscopic category, high resolution andbrightness can be obtained from both polarization-

multiplexed displays and the time-multiplexed shutter

glasses-based displays. As an example, dual-panel archi-

tecture (e.g., iZ3D), or those that use dual projectors can

have full resolution without any compromise in brightness.

In terms of the eyewear, passive glasses have the advantage

as they are simple and lightweight, do not require battery

replacement, and are low cost.Polarization-based flat panel displays (�-pol, active

retarder, etc.) typically lose half of the spatial resolution to

produce a stereo pair image. Furthermore, when those

displays are used in 2-D mode, 50% of the light is lost to

polarization components. When patterned micropolarizers

can be integrated into the panel production, the system

can be made more light efficient. Users are not likely to

give away the high-resolution and brightness advantages togo from 2-D to 3-D. Therefore, shutter-glass-based systems

have a resolution advantage over the polarization-based

systems. The drawbacks of the shutter-glass-based systems

are the requirement for faster LCD/LCOS switching times

and more complex and heavier shutter glasses that need

battery replacement. In this case, the major cost of the 3-D

capability is placed in the high-speed panels, electronics,

and eyewear. Which approach is better for an applicationdepends on many factors; passive eyewear may be more

favorable for applications where many people or long

duration use is involved.

For 3-D projection displays (rear projection and front

projection), full HD resolution can be maintained by

utilizing two projectors or a time-multiplexing scheme

with the help of a single-pixel polarization rotator in front

of the projection lens. The approach from HDI, for exam-ple, can be considered a hybrid between temporal and

polarization multiplexing. It features a dual-panel projec-

tion engine that allows polarization glass-based rear pro-

jection system and employs high-speed LCOS devices and

RGB laser illumination. The system provides 2-D/3-D

capability and uses simple low-cost polarization glasses

without sacrificing resolution or brightness.

2) Head-Mounted Systems: HMD optical design is

challenging due to the wide FOV and large exit pupil size

requirements in high-resolution displays. The size and

weight of HMDs are often quite large and the user comfort

is typically low. Displaying 3-D images on HMDs brings

additional challenges with subpixel accuracy requirements

in registration of images and optical distortion. Gaming is

Urey et al. : State of the Art in Stereoscopic and Autostereoscopic Displays

Vol. 99, No. 4, April 2011 | Proceedings of the IEEE 551

one important area for 3-D HMDs and there are alreadysuccessful products with a large FOV.

3) Autostereoscopic Technologies: For two-view and

multiview systems, simple 2-D/3-D switching should be

possible for a winning technology. For mobile and com-

puter monitor applications (e.g., gaming, CAD/CAM de-

sign, kiosk browsing, etc.), two-image systems should be

sufficient and multiview capability is not needed. A stereoimage pair that can change dynamically with the head-

tracked viewer head position could also be a winning

combination. For TV, cinema, or table-top 3-D displays,

multiview and multiviewer capabilities are important, but

current systems do not meet the needs of these segments.

4) Autostereoscopic Head-Tracked Displays: These enable

tracking of the viewing regions to follow the viewers’ eyesso that a pair of images is sufficient to display 3-D with

both horizontal and vertical parallax to the viewer. Motion

parallax can be achieved by presenting only as many

images as there are viewer eyes. This approach may require

dynamic optics/optomechanics, but it avoids displaying

large amounts of redundant information in contrast to

holographic displays. However, the processing required to

render images in accordance with the viewers’ eye posi-tions is challenging. At the present time, head-tracked

displays appear to provide a solution for multiviewer 3-D

until a fully holographic display is available.

5) Autostereoscopic Supermultiview Systems: These dis-

plays provide multiview and multiviewer capabilities but

they require more complex hardware and software com-

pared to two-view systems. SMV displays have the poten-tial to solve AC mismatch in order to provide more realistic

true 3-D display system. Providing two or more viewswithin each eye pupil can be done more easily if the pupil

is tracked and the light beams are redirected using dyna-

mic optics in the display system. If tracking is not em-

ployed, a large amount of information must be displayed in

order to provide true continuous motion parallax with no

AC mismatch. Currently, display panels do not have suffi-

cient native resolution to give this amount of information

without having to resort to the use of complex displayconfigurations. More research and development is needed

in this area. Early adaption of those technologies can be in

advertising, simulators, and gaming kiosks where higher

costs could be afforded.

6) Screen Technologies: Pico and mobile projectors are

advancing rapidly and there are already examples of 3-D

mobile displays and this seems to be an important futuredirection. We believe screen technologies that can form

separate viewing zones for each pupil are essential in order

to expand the capabilities of tiny projectors to 3-D. Note

that laser-based pico projectors are currently limited to

about ten lumens. Gain and ambient rejection capabilities

of screens will be critical for all battery operated devices.

Good candidate screen technologies for 3-D mobile dis-

plays can utilize microlens arrays and retroreflectors [127],[128]. We expect to see a lot of research activity in the area

of screens with special features. h

Acknowledgment

The authors would like to thank the HELIUM3D

consortium members. Feedback and comments from

C. Chinnock and K. Werner from Insight Media aregratefully acknowledged.

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ABOUT T HE AUTHO RS

Hakan Urey (Senior Member, IEEE) received the

B.S. degree from the Middle East Technical Univer-

sity, Ankara, Turkey, in 1992 and the M.S. and Ph.D.

degrees from Georgia Institute of Technology,

Atlanta, in 1996 and 1997, respectively, all in

electrical engineering.

Currently, he is a Professor of Electrical Engi-

neering at Koç University, Istanbul, Turkey. After

completing his Ph.D., he joined Microvision Inc.,

Seattle, WA, as a Research Engineer and he played

a key role in the development of the laser scanning display technologies.

He was the Principal System Engineer when he left Microvision to join the

faculty of engineering at Koç University, where he established the Optical

Microsystems Research Laboratory (OML). He published 35 journal and

about 80 conference papers, seven edited books, two book chapters, and

he has 20 issued and several pending patents. His research interests are

in optical microelectromechanical systems (MEMS), optical system de-

sign, and laser-based 2-D/3-D display and imaging systems, and

biosensors.

Dr. Urey received theWerner Von Siemens Faculty Excellence Award in

2006 from Koç University, the Distinguished Young Scientist award from

the Turkish Academy of Sciences in 2007, and the Encouragement Award

from the Scientific and Technical Research Council of Turkey (TUBITAK) in

2009. He is a member of The International Society for Optical Engineers

(SPIE), the Optical Society of America (OSA), IEEE-Photonics, and the Vice

President of the Turkey chapter of IEEE-Photonics.

Kishore V. Chellappan received the M.Sc. and

Ph.D. degrees in physics from Cochin University

of Science and Technology, Kerala, India, in 2002

and 2009, respectively.

He joined the Optical Microsystems Labora-

tory, Koç University, Istanbul, Turkey, in 2008,

where he contributed to the research and devel-

opment efforts of the EC funded BHELIUM3D[

laser-based display project. He is now a Re-

search Associate at the University of Southern

Mississippi, Hattiesburg. His research interests are in laser-based dis-

plays, optical system design, photorefractive polymers, photopolymers,

and infrared spectroscopy. He is a coauthor of several publications

including one book chapter.

Dr. Chellappan is a member of The International Society for Optical

Engineers (SPIE) and the Optical Society of America (OSA).

Erdem Erden (Student Member, IEEE) received

the B.Sc. degree in electrical and electronics

engineering and the M.Sc. degree in electrical

and computer engineering from Koç University,

Istanbul, Turkey, in 2008 and 2010, respectively.

Currently, he is working towards the Ph.D. degree

at the Center for Research and Education in Optics

and Lasers (CREOL), University of Central Florida,

Orlando.

He has worked at Optical Microsystems Labo-

ratory at Koç University as a Research Assistant between 2007 and 2010

and he has recently joined the Optical Fiber Communications Laboratory

at CREOL as a Graduate Research Assistant. His research interests are 3-D

displays, biophotonics, optical fiber telecommunication, and optical

microelectromechanical systems (MEMS).

Mr. Erden received the Vehbi Koç Foundation scholarship and the

Scientific and Technological Research Council of Turkey (TUBITAK)

scholarship during his studies.

Phil Surman received the B.Sc degree in electrical

and electronic engineering from Heriot-Watt

University, Edinburgh, U.K., in 1971 and the Ph.D.

degree in the subject of head-tracked 3-D dis-

plays from De Montfort University, Leicester, U.K.,

in 2003.

He has been investigating 3-D displays for the

last 23 years and holds the patents on the optical

systems for the MUTED and HELIUM3D displays.

He is currently a Senior Research Fellow in the

Imaging and Displays Research Group at De Montfort University and has

been involved in the European Union-funded ATTEST, 3D TV Network of

Excellence, MUTED and HELIUM3D projects that are all in the area of 3-D

displays.

Urey et al. : State of the Art in Stereoscopic and Autostereoscopic Displays

Vol. 99, No. 4, April 2011 | Proceedings of the IEEE 555